WO 2013/030276 describes a method for protecting Ethernet based critical data services during the transport over Ethernet based wide area networks WAN. The traffic in the source edge node of the WAN is duplicated by means of parallel redundancy protocol PRP. Both duplicates are sent via a fully redundant path over the WAN. In order to predefine such redundant path, multiple spanning tree protocol MSTP is used. In the destination edge node of the WAN, the duplicated packets are detected, and the first one to the intended data sink is sent while the second one that arrives is eliminated. This corresponds to the standard PRP functionality. The arrival of both entities of the same information, i.e. duplicated packets, is constantly checked in order to monitor the availability of both paths through the WAN. This also corresponds to standard PRP functionality.
PRP is a standardized protocol that can be used to duplicate Ethernet based traffic, send it over two distinct paths or networks, and based on predefined fields in the PRP packets eliminate duplicates.
FIG. 1 shows the current situation of non-Ethernet, non IEC61850 based communication of critical service, e.g. to protection relays, using legacy protocols such as E1, C37.94, X21, binary I/O or similar, between the interface of the WAN edge communication device to devices of the application of the critical service. The information of the critical data service to be transmitted is only converted to Ethernet based traffic inside an interworking function IWF inside the communication device.